Study of the impact of fatigue loading on the durability of aircraft slat membrane eyelets

A high-strength aluminum alloy 1933 being distinguished by good physicomechanical properties and high manufacturability is widely used in the most critical power aircraft structures, e.g., in a modern AN-148 SSJ aircraft. The alloy is used in production of various parts of articulated joints, thus making study of the durability of the alloy in a complex stress state a relevant goal. We present the results of static and dynamic tests of structurally similar samples (of two types) manufactured according to serial technology and corresponding to the shape of real eyelets of the airframe slats. Preliminary fatigue tests of standard samples (a strip with a hole) were performed to obtain the refined characteristics of the alloy in the T3 state. To analyze the mechanical behavior of the alloy with a different amplitude-frequency character of loading, the asymmetry of the loading cycle (R = 0.1; 0.2; 0.5; 0.6; 0.76; 0.82) and exposure frequencies (10, 60, and 100 Hz) were varied. In is shown that an increase in the average stress of the loading cycle reduced the number of cycles before the destruction of the eyelets: a 2-fold increase in the average stress resulted in a drop in fatigue life by two orders of magnitude (for an amplitude of 5 kg/mm2).